tree f81b9b1ca5095c506b16f4f2124b04058a4f9fe5
parent 74c274bf66fc9ff1193915913a3370bcc79dba51
author Jonathan Amsterdam <jba@google.com> 1475340879 -0400
committer Jonathan Amsterdam <jba@google.com> 1475772032 +0000

generator: support nulls in JSON

ForceSendFields doesn't quite cover all the cases needed to correctly
patch a resource. Sometimes you have to send a JSON null to clear a
value; the zero value won't do.

Two examples from storage/v1.Objects.Patch:

- It is an error to send "" as the value of ContentLanguage.

- Sending the empty JSON map `{}` for Metadata is a no-op.

In both these cases, to clear the value you must send a null.

This CL:

- Adds a NullFields field to each resource, to complement
  ForceSendFields.

- Modifies the custom JSON marshalling logic to send null for
  any field in NullFields (and return an error for a non-empty
  field in NullFields).

- Regenerates all the clients.

- Updates the goldens in testdata.

Change-Id: I748921ae83e2df6fb2f168a87075615955fcc656
Reviewed-on: https://code-review.googlesource.com/8010
Reviewed-by: Jonathan Amsterdam <jba@google.com>